Most Expensive Materials in the World — There are several extremely expensive substances in the world, and all of them have to do with exotic physics. Historical contenders for the most expensive substance such as saffron, plutonium, gold, and diamond are like dirt in comparison to these. Three categories of material that compete for the most expensive substance are antimatter (especially anti atoms like anti hydrogen), at $1,750 trillion US Dollars (USD) per ounce, followed by hafnium and tantalum isomers, at about $480 million USD per ounce, and assorted exotic particles such as bottom quarks, which are in the same league as antimatter.